1. Field of the Invention
The present invention relates to an antenna device which is most suitable for a television receiver mounted on an automobile.
2. Description of Prior Art
In an antenna device for a television receiver for an automobile, there are requirements of reduction of a phenomenon that a television image is disturbed during movement of the image by an influence of fading caused by a standing wave which takes place by interference between a direct radio wave from a transmission antenna and a radio wave reflected by buildings, mountains and the surface of land, a phenomenon of out of synchronization which gives difficulty in seeing a television image, a phenomenon of failing to receive a radio wave even when an automobile is stopped if an antenna is at a position corresponding the valley of a standing wave, a ghosting phenomenon causing double television images, and a TV fluttering phenomenon of movement of the ghost. Further, the antenna device should be small in size and light in weight and easily fitted to the automobile.
As an antenna device for a television receiver for an automobile to improve the above-mentioned points, there is known an antenna device as shown in FIG. 16 which is disclosed, for instance, in "Diversity receiving system for a color television receiver for an automobile" (a report of Television Society) published on May 27, 1982. The disclosed antenna device comprises two antennae 41, 42 each consisting of a plurality of elements, which are respectively attached to the left and right sides of the roof 44 of a car body 43, to perform diversity reception of signals by the two antennae 41, 42. However, the antenna device of this type is poor in appearance because two antennae 41, 42 consisting of a plurality of elements project upward from the car body 43 and is also dangerous. Further, it has such drawbacks of generation of sound caused by wind during a high speed cruising, being easily broken down by mischievous touch in parking, becoming an obstacle when the automobile is to be entered in a garage, and of being costly.